1. Technical Field
The present invention relates generally to a transformer fault detection apparatus and method. More particularly, the present invention relates to a transformer fault detection apparatus and method, in which a plurality of sensors are integrally mounted on a drain valve in the transformer, and which estimate the location of a partial discharge source in the transformer based on different signals sensed by the sensors.
2. Description of the Related Art
In order to detect an abnormal signal occurring due to the internal fault of a transformer, a scheme for installing an ultrasonic sensor on the enclosure of the transformer and measuring an abnormal signal, a scheme for installing an insertion-type Ultra High Frequency (UHF) electromagnetic sensor in the drain valve of the transformer and acquiring an abnormal signal, or a scheme for filling the inside of the transformer with insulating oil and remotely and periodically analyzing a dissolved gas, has been used, wherein a gas analysis device capable of detecting hydrogen or moisture is applied to some transformers.
In this case, when the ultrasonic sensor is attached to the enclosure of the transformer, there is a problem in that external noise from a power device in operation flows into the transformer, and thus it is difficult to identify a partial discharge signal. The UHF electromagnetic sensor to be inserted into the drain valve is disadvantageous in that sensors are required to be installed at two places, that is, the upper valve and the lower valve of the transformer, thus making it impossible to estimate the precise location of an abnormal signal. Further, the scheme for filling the inside of the transformer with insulating oil and analyzing a dissolved gas is disadvantageous in that it is impossible to monitor the internal abnormality of the transformer in real time, and some online gas analysis devices are foreign devices, and are thus expensive and difficult to maintain.
In particular, the detection of internal faults of the transformer using ultrasonic waves is configured such that when a partial discharge occurs in the transformer, surrounding insulating oil is suddenly compressed due to local heat generation around the partial discharge, and the location at which an abnormality has occurred can be estimated using a scheme for measuring pulse-shaped sound waves and ultrasonic waves occurring when shock waves attributable to such compression are transferred to the oil. However, there is a disadvantage in that it is impossible to measure the charge quantity of the partial discharge, and in that a precise correction of an estimated location is required due to the inflow of noise signals, such as external vibration or wind. Further, there is a fatal disadvantage in that it is difficult to distinguish a partial discharge signal caused by the internal defect of the transformer from an external noise signal, and thus such a scheme is still in a testing stage.
FIG. 1 is a diagram showing a method of detecting an internal defect of a conventional transformer.
In detail, when conventional technology is described with reference to FIG. 1, ultrasonic analysis equipment a, electromagnetic partial discharge analysis equipment b, and online gas analysis equipment c are located on a transformer T. In this case, since separate sensor devices are required to be installed depending on respective diagnosis schemes, the attachment, detachment, and maintenance of sensors is difficult, and each individual sensor is expensive, thus causing the problems of deteriorated diagnosis reliability and insufficient economic efficiency.
Therefore, there is required a transformer fault detection apparatus and method that can precisely estimate the location of a partial discharge source in a transformer by integrally mounting a plurality of sensors on a drain valve in the transformer and then sensing signals. As technology related to the present invention, there is Korean Patent Application Publication No. 2013-0034774.